Most major installations in the United States that use electrical power have backup systems in case the normal electrical supply becomes disabled. Typical examples include large office buildings, hospitals, public utility systems, and municipal facilities. Frequently, the source of the backup electrical power is a bank of interconnected electrolytic storage cells, such as the common lead-acid storage cell, which retain electrical charge for conversion to electrical current. Since it is often unpredictable when such systems will be called upon to supply their emergency function, it is critical that they be maintained at or near their greatest possible efficiency. Accordingly, the users of such systems have frequently put in place preventive maintenance and/or repair procedures.
Among the popular present methods for maintaining and/or repairing a large array of storage cells are: 1) to wait until some cell in the array fails; 2) to periodically replace the cells in the array, thereby reducing the chance that any one of the cells will fail when the array is called upon for its emergency purpose; or 3) to periodically test each cell in the array. A problem with the first method is that great expense can be incurred should the array fail when it is needed. A problem with second method is that it may be unnecessarily expensive and wasteful to periodically replace cells that may not be defective. A problem with the third method is that each individual cell must be separately checked with intrusive tests of the cell's electrolyte, which is typically a combination of various fluids such as water (H.sub.2 O) and sulfuric acid (H.sub.2 SO.sub.4).
Accordingly, it would be useful to have a method for monitoring and maintaining such arrays when and only when such services are required.